NBD Flashcards
What is a Non Directional Beacon (NBD) ?
Ground based transmitter that transmits radio energy in all directions.
What is an Automatic Direction Finder (ADF)?
Consists of:
1) A receiver with controls
2) An antennae
3) An Indicator
What does the antennae do?
Directs a needle on a cockpit indicator, indicating the position of the selected NBD beacon as a bearing from the centreline of the aircraft.
What acronym can be used to remember the limitations of ADF/NDB system?
M = Mountain effect I = Interference from other transmissions N = Night effect T = Thunderstorm Interference Q = Quadrantal Error C = Coastal Effects
What is mountain effect?
- When flying over mountains, an A/C may receive NDB signals that have been reflected from the surfaces of surrounding mountains and hills.
- This can cause erroneous and rapidly fluctuating bearing indications
What is interference from other transmissions?
NDBs of similar frequencies may be able to interfere with each other.
What is the night effect on NDBs?
Interference from sky waves that are reflected from the Ionosphere will cause significant error with the NDB.
Can night effect be elimintated?
No
What is thunderstorm interference?
- Thunderstorms can generate large amount of radio energy, especially in the LF and MF bands.
- This can cause the needle to fluctuate wildly.
What is quadrantal error?
Error where the transmissions strike the outer surfaces of the A/C, and are reflected in various directions, which then mix with the direct line signals received by the ADF itself.
What is coastal effects?
- Transmissions will tend to refract when going from water to land.
- Caused to bend towards the shore.
How does the Radio Magnetic Indicator (RMI) needle behave?
1) Needle always points to the NDB
2) The tail of the RMI needle indicates the bearing FROM the NDB
3) The needle indicates magnetic bearing
What is the process to use the NDB to navigate?
1) Identify an NDB nearby that may assist with navigation and that is within the rate coverage
2) Determine the frequency the NDB is using to broadcast
3) Determine the identified for the NDB
4) Continue to check the identifier as you use it for navigation.
What are the distance ranges of an NDB?
30 to 400 NM
What are the factors that influence signal transmission and reception range?
1) Transmitter power
2) Frequency of the signal (lower frequency means greater range)
3) Time of day
4) Type of surface over which the signals travel
5) Antenna Efficiency
